Your charisma determines how easy or hard it is. You can raise your stats every level...you get 3 points per level. So raise the charisma quickly.
You use the default "6" key to start the taming process. It displays a large circle with a smaller circle in the center. Using the arrow keys, you try to keep the icon within the smaller circle...it indicates which way you need to press to keep it centered. If you wander outside the small circle too much, the dragon gets angry and attacks. If you stay within the small circle enough, you "tame" (more like subdue!) the dragon and can then use it.
Also, you can use your dragon to fight along side of you but it is timed usage. Then there is a moderately long cool down timer before you can use it again...even for riding.
By the way, Dragons Prophet forums https://forums.station.sony.com/drag...-discussion.19
Hope this helps!